In a blast furnace system, a plurality of blast furnace stoves is operated at time-displaced cycles to heat a blast of air used to provide heat for a blast furnace. In each stove, there is a vertical combustion chamber coupled to a burner to inject gas, usually excess blast furnace gas, and air into the bottom portion of the chamber for combustion. Each stove is alternately on gas (being heated by combustion of the blast furnace gas) or on blast (heating the cold blast air). The combustion products are directed by a dome from the top of the combustion chamber into a regenerator through passageways in a filling of refractory checkerbrick to heat the blast of air. The blast of air usually flows through the openings in the checkerbrick countercurrent to the flow of combustion gases.
Generally, the heated air is withdrawn through an opening in the side wall of the combustion chamber. In such a blast furnace stove, the burner is usually arranged to direct the flame horizontally into the bottom of the vertically extending combustion chamber. A water-cooled burner valve opens and closes the passageway from the stove gas burner into the combustion chamber and provides thermal protection for the metal parts of the burner.
Typical blast furnace systems operate continuously for many years. But in many blast furnace systems the blast furnace stoves begin to deteriorate long before the end of the blast furnace campaign itself. Deteriorating blast furnace stoves' heating capacity will diminish and as a result the hot blast air supplied to the blast furnace will not be sufficiently hot for optimal operation of the blast furnace. This deterioration of the stoves require the blast furnace to burn more fuel to compensate for the lower hot blast temperature but after a certain level of deterioration of the stoves, the stoves must be repaired. The refractory work in the stove becomes plugged either from dirt in the blast furnace gas combustion products or falling and crumbling brickwork. The plugging reduces heat transfer surface area. The heat transfer efficiency of combustion flue gas heating the brick as well as the hot refractory heating the cold blast air diminishes as the refractory system becomes plugged. The net result is a lower hot blast temperature. In order to maintain the same production at the blast furnace more fuel must be added to the blast furnace. The fuel can be in the form of additional metallurgical coke with the top solid charging or by fossil fuels that are added near the hot blast tuyeres. The stoves may consume less fuel during heating. But, repairs to a stove generally can be carried out only after the stove is cooled to near ambient temperature, which means that the stove can not be operating. This long interruption to the operation of the stove substantially affects the blast furnace's economical operation.
Thus, an improved blast furnace system is desired.